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Infiniti VH45DE specs: 4.5L (274.2 ci) 8-cylinder, 93 x 82.7 mm (3.6610 x 3.2560 in) bore and stroke, 10.2:1 compression. Rated 278 hp. DOHC.
The Infiniti VH45DE is oversquare — the 3.661" bore exceeds the 3.256" stroke by 12.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.256" stroke does not reach 4,000 ft/min of mean piston speed until about 7,350 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 34.3 ci (562 cc).
10.2:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 3 engines in the VH family, the largest at 274.2 ci. Factory fitments include the Infiniti Q45.
| Displacement | 274.2 ci / 4.5 L |
|---|---|
| Bore | 3.661" |
| Stroke | 3.256" |
| Cylinders | 8 |
| Compression ratio | 10.2:1 |
| Bore/stroke ratio | 1.124 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 278 hp |
| Bore/stroke character | 1.124 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,256 ft/min — conservative for a street engine |
| Displacement per cylinder | 34.3 ci |
| Static compression | 10.2:1 — in the range that usually runs on pump premium |
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